US5536578A - Magnetic recording medium comprising a protective layer and a layer of ammonium carboxylate fluorine-containing compound - Google Patents

Magnetic recording medium comprising a protective layer and a layer of ammonium carboxylate fluorine-containing compound Download PDF

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US5536578A
US5536578A US08/381,277 US38127795A US5536578A US 5536578 A US5536578 A US 5536578A US 38127795 A US38127795 A US 38127795A US 5536578 A US5536578 A US 5536578A
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medium
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Mitsuyoshi Shoji
Takayuki Nakakawaji
Hiroshi Sasaki
Yutaka Ito
Shigeki Komatsuzaki
Hiroyuki Matsumoto
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HGST Japan Ltd
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Hitachi Ltd
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    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10M—LUBRICATING COMPOSITIONS; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION
    • C10M105/00—Lubricating compositions characterised by the base-material being a non-macromolecular organic compound
    • C10M105/56—Lubricating compositions characterised by the base-material being a non-macromolecular organic compound containing nitrogen
    • C10M105/70—Lubricating compositions characterised by the base-material being a non-macromolecular organic compound containing nitrogen as ring hetero atom
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10M—LUBRICATING COMPOSITIONS; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION
    • C10M105/00—Lubricating compositions characterised by the base-material being a non-macromolecular organic compound
    • C10M105/56—Lubricating compositions characterised by the base-material being a non-macromolecular organic compound containing nitrogen
    • C10M105/58—Amines, e.g. polyalkylene polyamines, quaternary amines
    • C10M105/64—Amines, e.g. polyalkylene polyamines, quaternary amines having amino groups bound to a carbon atom of a six-membered aromatic ring
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B5/00—Recording by magnetisation or demagnetisation of a record carrier; Reproducing by magnetic means; Record carriers therefor
    • G11B5/62—Record carriers characterised by the selection of the material
    • G11B5/72—Protective coatings, e.g. anti-static or antifriction
    • G11B5/725—Protective coatings, e.g. anti-static or antifriction containing a lubricant, e.g. organic compounds
    • G11B5/7253—Fluorocarbon lubricant
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B5/00—Recording by magnetisation or demagnetisation of a record carrier; Reproducing by magnetic means; Record carriers therefor
    • G11B5/62—Record carriers characterised by the selection of the material
    • G11B5/72—Protective coatings, e.g. anti-static or antifriction
    • G11B5/726—Two or more protective coatings
    • G11B5/7262—Inorganic protective coating
    • G11B5/7264—Inorganic carbon protective coating, e.g. graphite, diamond like carbon or doped carbon
    • G11B5/7266—Inorganic carbon protective coating, e.g. graphite, diamond like carbon or doped carbon comprising a lubricant over the inorganic carbon coating
    • C—CHEMISTRY; METALLURGY
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    • C10M2213/00—Organic macromolecular compounds containing halogen as ingredients in lubricant compositions
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    • C10M2213/00—Organic macromolecular compounds containing halogen as ingredients in lubricant compositions
    • C10M2213/04—Organic macromolecular compounds containing halogen as ingredients in lubricant compositions obtained from monomers containing carbon, hydrogen, halogen and oxygen
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10M—LUBRICATING COMPOSITIONS; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION
    • C10M2213/00—Organic macromolecular compounds containing halogen as ingredients in lubricant compositions
    • C10M2213/06—Perfluoro polymers
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10N—INDEXING SCHEME ASSOCIATED WITH SUBCLASS C10M RELATING TO LUBRICATING COMPOSITIONS
    • C10N2040/00—Specified use or application for which the lubricating composition is intended
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10N—INDEXING SCHEME ASSOCIATED WITH SUBCLASS C10M RELATING TO LUBRICATING COMPOSITIONS
    • C10N2040/00—Specified use or application for which the lubricating composition is intended
    • C10N2040/14—Electric or magnetic purposes
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10N—INDEXING SCHEME ASSOCIATED WITH SUBCLASS C10M RELATING TO LUBRICATING COMPOSITIONS
    • C10N2040/00—Specified use or application for which the lubricating composition is intended
    • C10N2040/14—Electric or magnetic purposes
    • C10N2040/16—Dielectric; Insulating oil or insulators
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10N—INDEXING SCHEME ASSOCIATED WITH SUBCLASS C10M RELATING TO LUBRICATING COMPOSITIONS
    • C10N2040/00—Specified use or application for which the lubricating composition is intended
    • C10N2040/14—Electric or magnetic purposes
    • C10N2040/17—Electric or magnetic purposes for electric contacts
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10N—INDEXING SCHEME ASSOCIATED WITH SUBCLASS C10M RELATING TO LUBRICATING COMPOSITIONS
    • C10N2040/00—Specified use or application for which the lubricating composition is intended
    • C10N2040/14—Electric or magnetic purposes
    • C10N2040/175—Pantographs, i.e. printing devices
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
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    • C10N2040/00—Specified use or application for which the lubricating composition is intended
    • C10N2040/14—Electric or magnetic purposes
    • C10N2040/18—Electric or magnetic purposes in connection with recordings on magnetic tape or disc
    • C—CHEMISTRY; METALLURGY
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    • C10N2040/00—Specified use or application for which the lubricating composition is intended
    • C10N2040/14—Electric or magnetic purposes
    • C10N2040/185—Magnetic fluids
    • C—CHEMISTRY; METALLURGY
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    • C10N—INDEXING SCHEME ASSOCIATED WITH SUBCLASS C10M RELATING TO LUBRICATING COMPOSITIONS
    • C10N2040/00—Specified use or application for which the lubricating composition is intended
    • C10N2040/30—Refrigerators lubricants or compressors lubricants
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    • C10N2040/32—Wires, ropes or cables lubricants
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    • C10N2040/00—Specified use or application for which the lubricating composition is intended
    • C10N2040/34—Lubricating-sealants
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
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    • C10N2040/00—Specified use or application for which the lubricating composition is intended
    • C10N2040/36—Release agents or mold release agents
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10N—INDEXING SCHEME ASSOCIATED WITH SUBCLASS C10M RELATING TO LUBRICATING COMPOSITIONS
    • C10N2040/00—Specified use or application for which the lubricating composition is intended
    • C10N2040/38—Conveyors or chain belts
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10N—INDEXING SCHEME ASSOCIATED WITH SUBCLASS C10M RELATING TO LUBRICATING COMPOSITIONS
    • C10N2040/00—Specified use or application for which the lubricating composition is intended
    • C10N2040/40—Generators or electric motors in oil or gas winning field
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10N—INDEXING SCHEME ASSOCIATED WITH SUBCLASS C10M RELATING TO LUBRICATING COMPOSITIONS
    • C10N2040/00—Specified use or application for which the lubricating composition is intended
    • C10N2040/42—Flashing oils or marking oils
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10N—INDEXING SCHEME ASSOCIATED WITH SUBCLASS C10M RELATING TO LUBRICATING COMPOSITIONS
    • C10N2040/00—Specified use or application for which the lubricating composition is intended
    • C10N2040/44—Super vacuum or supercritical use
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10N—INDEXING SCHEME ASSOCIATED WITH SUBCLASS C10M RELATING TO LUBRICATING COMPOSITIONS
    • C10N2040/00—Specified use or application for which the lubricating composition is intended
    • C10N2040/50—Medical uses
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10S428/00—Stock material or miscellaneous articles
    • Y10S428/90—Magnetic feature
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T428/00—Stock material or miscellaneous articles
    • Y10T428/30—Self-sustaining carbon mass or layer with impregnant or other layer
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T428/00—Stock material or miscellaneous articles
    • Y10T428/31504—Composite [nonstructural laminate]
    • Y10T428/3154—Of fluorinated addition polymer from unsaturated monomers
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T428/00—Stock material or miscellaneous articles
    • Y10T428/31504—Composite [nonstructural laminate]
    • Y10T428/3154—Of fluorinated addition polymer from unsaturated monomers
    • Y10T428/31544—Addition polymer is perhalogenated

Definitions

  • the present invention relates to an ammonium carboxylate type fluorine-containing compound, a surface modifier for improving the hydrophobic property, oilphobic property and lubricity of solid surfaces, and a magnetic recording medium using the same. Particularly, it relates to the improvement of the sliding durability of a magnetic recording medium having a carbon protective film as the outermost layer.
  • a is 3 to 12 and P is a polar group of various types including --SO 2 K, --SO 2 Na, --SO 2 F, --COOH, --SO 3 H, --OH and the like, as described in JP-A-61-42727, JP-A-58-29147 and JP-A-2-145550. All the perfluoroalkyl type compounds disclosed in the documents, however, have a short fluorocarbon chain with a carbon number (a) of 3 to 12.
  • the compounds are poor in effectiveness when used for modifying the lubricity of the friction surface of a solid material, although they are highly effective in preventing the contamination on the surface of a solid material and in imparting hydrophobic property and oilphobic property to the surface of a solid material.
  • the carbon number is as large as 30 to 120, and the modified surface has a good lubricity.
  • This type of modification methods include, for example,
  • magnetic recording media are being used in wide fields for information memory playback apparatuses of large capacity.
  • thin layer magnetic recording media with a high magnetic recording density are used.
  • magnetic disk apparatuses are required to have a particularly high recording density and a high-speed data uptake.
  • the gap between the head and the disk is narrowed and subsequently the probability of causing contact sliding is raised by the increase of memory capacity.
  • the trend makes severe the conditions under which thin layer magnetic recording media are used. Therefore, the improvement of sliding durability thereof is an indispensable factor.
  • lubricants are difficultly fixed to the surface of the protective film by adsorption or by chemical reaction.
  • the protective film is a film containing a chemically stable carbon allotrope, fixing lubricants to the surface is more difficult. Due to this, lubricants are apt to detach from the surface of the protective layer and hence a sufficient sliding durability cannot be obtained.
  • fluorine-containing lubricants cover the surface thereof in an undesirably low rate. This is because the surface of inorganic oxide film is hydrophilic whereas the fluorine-containing lubricants have hydrophobic property.
  • the known methods of surface modification that improve the sliding durability of a magnetic recording medium are classified into two types.
  • One uses a lubricant containing a compound having perfluoroalkyl of short fluorocarbon chain.
  • the other uses a lubricant containing a compound having perfluoropolyoxyalkyl or perfluoropolyoxyalkylene of long fluorocarbon chain.
  • the lubricity obtained by the use of a compound having perfluoroalkyl of short fluorocarbon chain is lower than the lubricity obtained by the use of a compound having a long fluorocarbon chain.
  • the compound having perfluoroalkyl of short fluorocarbon chain is used incorporated into the binder layers of magnetic tapes and coating-type magnetic disks.
  • the methods of surface modification of this type have been proposed in a large number.
  • a recent proposal JP-A-64-9961 teaches that surface treatment with a fluorine surface modifier containing a compound having as a functional group an ammonium perfluoroalkylcarboxylate of 3-12 carbon atoms of the formula,
  • lubricants containing a compound having a perfluoropolyoxyalkyl of long fluorocarbon chain or a perfluoropolyoxyalkylene of long fluorocarbon chain are utterly insoluble in non-fluorine-containing organic solvents. Therefore, disadvantageously, they cannot be used incorporated in a coating material. They are coated on a solid surface, and many patent proposals have been made for their use in magnetic recording media. Of the proposals, there is a method of surface modification wherein a compound having perfluoropolyoxyalkyl contained in a lubricant is chemically fixed to the surface of a magnetic disk (U.S. Pat. No. 4,120,995).
  • the proposed lubricant shows a good lubricating property due to their long fluorocarbon chain, the lubricity is lost once the compound is detached from the surface by collision between the head and the disk.
  • lubricants are desired to have a self-recovering property such that the lubricant detached from the sliding surface can return again to the sliding surface.
  • lubricants which have an appropriate adsorbability are required.
  • the surface is covered with a protective film formed by vapor deposition or sputtering, the lubricant can be poorly adsorbed on the surface.
  • the adsorbability of the lubricant is further reduced due to the chemical stability of the carbon allotropes contained in the film. Accordingly, conventionally in practical use, the surface of a protective film has been pretreated in order to enhance the adsorbability of the lubricant.
  • the protective film is an oxide film formed by vapor deposition or sputtering
  • the oxide film has a good adsorbability for lubricants.
  • the film also has a strong affinity to water. Therefore, undesirably, penetration of water into the interface between the lubricant and the inorganic oxide results in unsatisfiactory formation of a hydrophobic surface.
  • the rate of surface covering by the lubricant is poor.
  • the use of fluorine-containing solvents is inevitable due to the insolubility of lubricants containing a segment having perfluoropolyoxyalkyl of long fluorocarbon chain or perfluoropolyoxyalkylene of long fluorocarbon chain in organic solvents. It disadvantageously makes the surface modification process costly and makes difficult the waste liquid disposal.
  • the objects of the present invention are to provide a novel fluorine-containing compound that can overcome the disadvantages of the prior art discussed above; to provide a surface modifier containing the compound which can impart a high hydrophobic property and oilphobic property, and in particular a high lubricity to the surface of a solid; and to provide a magnetic recording medium having an improved sliding durability.
  • R f is a perfluoropolyoxyalkyl chain having a number average molecular weight of at least 800, n is a number of 1-2, and R is a residue selected from the group consisting of an aromatic ammonium which may have one or more substituents at the nucleus, benzylammonium which may have one or more substituents at the nucleus, dibenzylammonium which may have one or more substituents at the nucleus, tribenzylammonium which may have one or more substituents at the nucleus and an aromatic inium which may have one or more substituents at the nucleus;
  • R f , n and R are as defined above,
  • a protective layer formed on the magnetic substance layer which comprises at least one member selected from the group consisting of inorganic oxides, graphite and amorphous allotropes of carbon, and
  • R f , n and R are as defined above;
  • R f , n and R are as defined above, and
  • a protective layer formed on the magnetic substance layer which comprises at least one member selected from the group consisting of inorganic oxides, graphite and amorphous allotropes of carbon, with a solid surface modifier comprising
  • R f , n and R are as defined above, and
  • FIGS. 1A and 1B show NMR spectra of the fluorine-containing compound of Example 1 of the present invention, FIG. 1A referring to the 19 F-NMR spectrum and FIG. 1B referring to the 1 H-NMR system.
  • FIGS. 2A and 2B show NMR spectra of the fluorine-containing compound of Example 2 of the present invention, FIG. 2A referring to the 19 F-NMR spectrum and FIG. 2B referring to the 1 H-NMR system.
  • FIGS. 3A and 3B show NMR spectra of the fluorine containing compound of Example 3 of the present invention, FIG. 3A referring to the 19 F-NMR spectrum and FIG. 3B referring to the 1 H-NMR spectrum.
  • FIGS. 4A and 4B show NMR spectra of the fluorine-containing compound of Example 4 of the present invention, FIG. 4A referring to the 19 F-NMR spectrum and FIG. 4B referring to the 1 H-NMR spectrum.
  • the above-mentioned objects have been attained by using the compound of the formula (A) which contains (i) an ammonium carboxylate residue having at least one aromatic ring or at least one nitrogen-containing heterocyclic ring and (ii) one or more perfluoropolyoxyalkyl or perfluoropolyocyalkylene chains, wherein the residue (i) is bonded to one or more molecular ends of the residue (ii) so that the compound (A) has a chemical structure that enables easy adsorption on the surface of a solid, by inventing a water-soluble surface treating agent containing the compound, and further by completing a magnetic recording medium using the surface treating agent.
  • the above-mentioned magnetic recording medium includes a non-magnetic substrate, one or more magnetic layers formed on the substrate, a protective film formed on the magnetic layer(s), and a fluorine-containing layer containing the surface treating agent containing the compound of the present invention provided on the protective layer.
  • a fluorine-containing film with a high hydrophobic property, oilphobic property and lubricity can be formed as follows.
  • the compound of the formula (A) which has a structure wherein the residue (i) an ammonium carboxylate residue having at least one aromatic ring or at least one nitrogen-containing heterocyclic ring is bonded to one or more molecular ends of the residue (ii) one or more perfluoropolyoxyalkyl or perfluoropolyoxyalkylene chains, is dissolved in an aqueous solution containing an alcohol (e.g. methanol and ethanol). The alcohol solution is coated on the surface to be treated and then the solvent is removed, for example by drying.
  • an alcohol e.g. methanol and ethanol
  • the solvent there may be used an alcohol (e.g. methanol and ethanol) alone or, alternatively, a fluorine-containing solvent alone.
  • the respective solvents can be used properly according to the intended uses.
  • the solvent used may be a mixture of at least one alcohol and water. In this case, the content of water may be freely selected within the range of from 0% by weight exclusive to 95% by weight inclusive.
  • perfluoropolyoxyalkyl and perfluoropolyoxyalkylene chains referred to in the present invention includes the chains contained in the Krytox series polymers (available from E. I. du Pont de Nemours Co.).
  • the Krytox resins polymers have a perfluoropolyoxypropylene chain represented by the following formula,
  • d is an integer of 1 or more.
  • the chains are not limited thereto.
  • a mixed system of perfluoropolyoxypropyl and perfluoropolyoxyethylene include the chains contained in the Fomblin Z series polymers manufactured by Monte Fluos Corp.
  • the Fomblin Z series polymers have the chain represented by the following formula,
  • perfluoropolyoxypropyl examples include the chains contained in the Demnam series polymers manufactured by Daikin Industries Ltd.
  • the Demnam series polymers have the chain represented by the following formula,
  • a practically useful range of molecular weight is at least 800, preferably between 800 inclusive and 10,000 inclusive.
  • ammonium carboxylate type fluorine-containing compound of the present invention is a compound having the formula,
  • R f is a perfluoropolyoxyalkyl chain having a number average molecular weight of at least 800, n is a number of 1-2, and R is a residue selected from the group consisting of an aromatic ammonium which may have one or two substituents at the nucleus, benzylammonium which may have one or more substituents at the nucleus, dibenzylammonium which may have one or more substituents at the nucleus, tribenzylammonium which may have one or more substituents at the nucleus and an aromatic inium which may have one or more substituents at the nucleus.
  • the compound is an ammonium carboxylate type fluorine-containing compound of the formula, ##STR1## wherein R f is a perfluoropolyoxyalkyl chain having a number average molecular weight of at least 800, n is a number of 0-2, R a is a direct single bond or methylene group, and A and B are independently hydrogen, methoxy, nitro, halogeno, C 1 --C 18 alkyl, phenoxy or benzyl.
  • R f is preferably a perfluoropolyoxyalkyl chain of a number average molecular weight falling within the range of from 800 inclusive to 10,000 inclusive. More preferably, it is a perfluoropolyoxyalkyl chain having the repeating unit:
  • R denotes phenylammonium, diphenylammonium, triphenylammonium, benzylammonium, dibenzylammonium, tribenzylammonium, pyridinium, qunolinium, isoquinolinium, acridinium, naphthyridinium, 4,4'-bipyridinium, 2,2'-bipyridinium, or bipyridinium bridged by --CO--; or one of the said groups having at the aromatic nucleus one or two substituents selected from methoxy, C 1 --C 18 alkyl, halogeno, nitro, benzyl and phenoxy, provided that when the aromatic nucleus is substituted with two substituents, the substituents may be the same or different.
  • it denotes phenylammonium, benzylammonium, pyridinium, quinolinium or acridinium, or the above-mentioned groups having at the aromatic nucleus one or two substituents selected from methoxy, C 1 --C 18 alkyl, halogeno, nitro, benzyl and phenoxy, provided that when the aromatic nucleus is substituted with two substituents, the substituents may be the same or different.
  • the ammonium carboxylate group in the surface modifier of the present invention is strongly polarized. Therefore, the modifier is strongly adsorbed to the adsorption site (e.g. hydroxy group etc.) on the surface of a solid to which it is adsorbed. At the same time, the aromatic ring attached to the ammonium carboxylate group or the nitrogen-containing hetero-ring with aromaticity shows a strong affinity to the carbon in the protective film. Therefore, the modifier is strongly adsorbed on the protective film of a magnetic recording medium when the protective film contains carbon.
  • the adsorption site e.g. hydroxy group etc.
  • the perfluoropolyoxyalkyl or perfluoropolyoxyalkylene chain as a lubricating segment and the aromatic ring attached to the ammonium carboxylate group or the nitrogen-containing hetero-ring with aromaticity are hydrophobic. Therefore, water can hardly penetrate into the neighborhood of the ammonium carboxylate groups. As a result, the oxide film, when used as a protective layer, can be kept sufficiently hydrophobic.
  • the surface of the body which has been modified with the above-mentioned surface modifying material containing the fluorine-containing compound is covered with perfluoropolyoxyalkylene film. It exhibits a sufficient hydrophobic property, oilphobic property and lubricity over a long period of time. This advantage is satisfactorily obtained either for a film containing carbon and an oxide film when they are used as the protective film of a magnetic recording medium.
  • the surface-modification exerts, besides the effect of enhancing hydrophobic property, oilphobic property and lubricity, also a corrosion preventive effect.
  • the corrosion preventive effect brings a bonus effect on a magnetic recording medium, which tends to be damaged by corrosion. Accordingly, magnetic storage devices provided with the magnetic recording medium of the present invention can be expected to have a high sliding durability, corrosion resistance and hence enhanced reliability.
  • the solution (I) and 100 g of methanol were placed in a 500-ml separatory funnel, then thoroughly stirred and allowed to stand for 1 hour. After standing, the solution in the separatory funnel separated into two layers, and a solution (II) was obtained from the lower layer.
  • the solution (II) was placed in an evaporator and the solvent (perfluorohexane) was removed, whereby about 15 g of a pale brown, highly viscous liquid fluorine-containing compound having the structure of the formula 14 shown before was obtained.
  • the compound had a viscosity of 169 ⁇ 10 5 m 2 /s at 40° C.
  • the structure of the fluorine-containing compound was investigated from the 19 F-NMR spectrum of FIG. 1A and the 1 H-NMR spectrum of FIG. 1B.
  • FIG. 1A the spectrum of fluorine at the position 3 shifted toward the lower magnetic field side as compared with the spectrum at the position 1, revealing that no unreacted carboxylic acid remained (in the case of unreacted carboxylic acids, in contrast, the spectrum at the position 3 shifts toward the higher magnetic field side than the position 1).
  • the presence of phenoxyphenol can be confirmed, while no spectrum of amide (in the vicinity of 9-13 ⁇ m) was observed.
  • the structure of the formula 14 was identified.
  • the compound has a characteristic feature of being soluble in methanol in spite of being a fluorine-containing compound of a high molecular weight; further it is soluble also in 10% aqueous methanol solution.
  • the fluorine-containing compound of the present invention was examined for its properties as a surface modifier.
  • a substrate (I) was prepared which comprised an aluminum alloy substrate and an amorphous silicon film of 1 ⁇ m thickness formed thereon.
  • the substrate (I) was dip-coated in a 0.2% by weight solution of the fluorine-containing compound of this Example in perfluorohexane under conditions of a dip time of 60 sec and draw-out velocity of 1 mm/sec.
  • the dipped substrate was dried at room temperature for 1 hour.
  • the surface tension of the surface thus coated was determined with water and a silicone oil (G747, mfd. by Shin-etsu Chemical Co.), respectively, for its hydrophobicity and oilphobicity. The results are shown in Table 1.
  • the structure of the fluorine-containing compound was investigated from the 19 F-NMR spectrum of FIG. 2A and the 1 H-NMR spectrum of FIG. 2B.
  • FIG. 2A the spectrum of fluorine at the position 3 shifted toward the lower magnetic field side as compared with the spectrum at the position 1, revealing that no unreacted carboxylic acid remained (in the case of unreacted carboxylic acids, the spectrum at the position 3 shifts toward the higher magnetic field side than the position 1).
  • the presence of tribenzyl groups could be confirmed, while no spectrum of amides (in the vicinity of 9-13 ⁇ m) was observed.
  • the structure of the formula 15 was identified.
  • This compound similarly to that of Example 1, has a characteristic feature of being soluble in methanol.
  • the structure of the fluorine-containing compound was investigated from the 19 F-NMR spectrum of FIG. 3A and the 1 H-NMR spectrum of FIG. 3B.
  • FIG. 3A the spectrum of fluorine at the position 3 shifted toward the lower magnetic field side as compared with the spectrum at the position 1, revealing that no unreacted carboxylic acid remained (in the case of unreacted carboxylic acid, the spectrum at the position 3 shifts toward the higher magnetic field side than the position 1).
  • the presence of pyridine groups could be confirmed.
  • the structure of the formula 7 was identified.
  • This compound similarly to that of Example 1, has a characteristic feature of being soluble in methanol.
  • Example 2 In the same manner as in Example 1, about 15 g of a pale brown, transparent, highly viscous fluorine-containing compound represented by the formula 18 shown before was obtained from 15.4 g (0.008 mol) of Krytox 157 FS-L (number average molecular weight: 1,920) and 1.5 g (0.0116 mol) of isoquinoline. The compound had a viscosity of 365.2 ⁇ 10 6 m 2 /s at 40° C.
  • the structure of the fluorine-containing compound was investigated from the 19 -NMR spectrum of FIG. 4A and the 1 H-NMR spectrum of the FIG. 4B.
  • FIG. 4A the spectrum of fluorine at the position 3 shifted toward the lower magnetic field side as compared with the spectrum at the position 1, revealing that no unreacted carboxylic acid remained (in the case of unreacted carboxylic acid, the spectrum at the position 3 shift toward the higher magnetic field side than the position 1).
  • the presence of the isoquinoline ring could be confirmed.
  • the structure of the formula 18 was identified.
  • Krytox 257FS-L and Fomblin Z-DI were reacted with a variety of amines (I) shown in Table 5, including various anilines and various pyridines, quinolines and acridine having a heterocyclic ring, some of the amines having benzyl.
  • the amines were reacted in excess of about 1.5 moles relative to 1 mole of the carboxylic acid of Krytox or Fomblin.
  • the structure as well as the viscosity, hydrophobicity and oilphobicity of the products are shown in Table 5.
  • Disks having a magnetic layer were prepared by providing on the surface of an Al alloy disk of 5.25 inch diameter a Ni--P layer and further thereon a Co layer, then sputtering thereon a Ni--Co magnetic layer in 50 nm thickness and further forming a carbon film in 50 nm thickness thereon. Then, the fluorine-containing surfactants obtained in Examples 1, 2 and 5 were respectively dissolved in perfluorohexane to a concentration of 0.2% by weight to prepare solutions. The disk prepared above was dipped in the solution to be coated with the surface modifier in a film thickness of 10 ⁇ 2 nm. The dip time was 60 sec. and the draw-up velocity was 1 mm/sec.
  • the adsorbability of these surface modifiers to carbon film was evaluated by their thermal weight loss. That is, the disk having the modifier film was heated at 100° C. and the percentage of film thickness decrease caused by heating was determined. The adsorbability was evaluated from the film thickness after 100 hours of heating. Separately, the sliding property as an actual disk was evaluated by CSS method (contact-start-stop test method).
  • the test machine used was the one made by Onoda Cement Co., Ltd. The test conditions were as follows: (1) number of rotation: 3,600 ppm, (2) 1 cycle: 30 sec., (3) number of final cycle: 1,000 cycle, and (4) head load: 10 g.
  • the sliding property was evaluated by the frictional force at the time of stiction in the final cycle.
  • Table 6 reveals that the fluorine-containing surface modifiers of the present invention show a lower thermal weight loss and hence a higher adsorbability and also have a better CSS characteristic than those used in Comparative Examples.
  • the molecular structures of AM 2001 and Krytox 143 AB are, respectively, as follows.
  • Disks having a magnetic layer were prepared by providing on the surface of an Al alloy disk of 5.25 inch diameter a Ni--P layer and further thereon a Co layer, then sputtering thereon a Ni--Co magnetic layer in 50 nm thickness and further forming a SiO 2 film in 50 nm thickness thereon. Then, the compound No. 6 of Example 5 was dissolved in perfluorohexane to a concentration of 0.2% by weight, and the disk prepared above was dipped in the solution to be coated with the surface modifier in a film thickness of 10 ⁇ 2 nm. The dip time was 60 sec. and the draw-up velocity was 1.5 mm/sec. The surface tension of the surface of the film thus formed was determined with water and a silicone oil (G747, mfd. by Shin-etsu Chemical Co.) for its hydrophobicity and oilphobicity. The results obtained are shown in Table 7.
  • Example 2 In the same manner as in Example 1, a disk (I) having an amorphous silicon film formed thereon was prepared. Then, a coating solution of 0.1% by weight concentration was prepared by dissolving the compound No. 5 of Example 5 in 10% aqueous methanol solution. The disk prepared above was dipped in the solution to be coated with the surface modifier in a film thickness of 10 ⁇ 2 mm. The dip time was 60 sec, and the draw-up velocity was 1 mm/sec. The surface tension of the surface of the film thus formed was determined with water and an silicone oil (G747, mfd. by Shin-etsu Chemical Co.) for the hydrophobicity and oilphobicity of the surface. The results obtained are shown in Table 8.
  • the substrate (I) itself as in Examples 1 and 2.
  • the results reveal that when the surface treating agent of the present invention is used, the treated surface shows larger contact angles for both water and silicone oil. Thus, it shows higher hydrophobic property and oilphobic property than the control.
  • a disk having a magnetic layer was prepared by providing on the surface of an Al alloy disk of 5.25 inch diameter a Ni--P layer and further thereon a Co layer, then sputtering thereon a Ni--Co magnetic layer in 50 nm thickness, and further forming a carbon film in 50 nm thickness thereon. Then, the fluorine-containing surfactant obtained in Example 1 was dissolved in perfluorohexane to a concentration of 0.15, 0.2, 0.25 and 0.3% by weight, respectively, to prepare solutions. The disk prepared above was dipped in each of the solutions to be coated with the modifier under dipping conditions of a dip time of 60 sec, and draw-up velocity of 1 mm/sec.
  • the magnetic recording media thus obtained had a film thickness of surface modifier of 6.8, 10.2, 15.5 and 32.5 nm, respectively.
  • the relation between the film thickness and the sliding property was examined by the CSS method (contact-start-stop test method) with a testing apparatus made by Onoda Cement Co., Ltd.
  • the test conditions were as follows: (1) number of rotation: 3,600 rpm, (2) 1 cycle: 30 sec., (3) number of final cycle: 1,000, (4) head load: 10 g.
  • the sliding property was evaluated by determining the frictional force at the time of stiction in the initial and the final cycle. The results obtained are shown in Table 9.
  • the film thickness was 32.5 nm, the tangential force was as large as 30 g or more and the CSS characteristic could not be evaluated. It has been revealed, therefore, that the film thickness of the surface modifier, as used in magnetic recording media, must be not more than 30 nm, at least.
  • n is average 21, and stirred thoroughly.
  • a solution of 2.3 g of 4,4'-bipyridyl (molecular weight: 156) in 10 g of methanol was added dropwise a solution of 2.3 g of 4,4'-bipyridyl (molecular weight: 156) in 10 g of methanol, and thorough stirring was continued at room temperature for 1 hour.
  • the fluorine-containing compound of the present invention was examined for its property as a surface modifier.
  • a substrate [I] was prepared by forming an amorphous silicon film of 1 ⁇ m thickness on an aluminum alloy substrate, and dip-coated with a 0.2% by weight solution of the compound No. 13 in perfluorohexane solvent under coating conditions of a dip time of 60 sec, and draw-up velocity of 1 mm/sec.
  • the surface tension of the surface of the film thus formed was determined with water and a silicone oil (G 747, mfd. by Shin-etsu Chemical Co.) for its hydrophobicity and oilphobicity. The results are shown in Table 10.
  • the compounds of the present invention are, as a fluorine-containing surface modifier, excellent in adhesiveness to carbon and moreover excellent in lubricity, hydrophobic property and oilphobic property.
  • the sliding durability of magnetic recording media is improved and thus magnetic recording media having high reliability and high recording density can be obtained.

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US5830834A (en) * 1991-11-07 1998-11-03 Hitachi, Ltd. Ammonium carboxylate type fluorine-containing compound, solid surface modifier containing the same and magnetic recording medium using the same
US20040044122A1 (en) * 2002-08-29 2004-03-04 Boldt Brent R. Ultraviolet radiation curable coating for MLS head gasket applications
US6761974B1 (en) 2001-05-04 2004-07-13 Seagate Technology Llc Polymeric lubricants with improved stability and thin film recording media comprising same
US20100246064A1 (en) * 2009-03-27 2010-09-30 Hoya Corporation Lubricant compound for a magnetic disk, magnetic disk, and method of manufacturing the same
US20120231297A1 (en) * 2011-03-07 2012-09-13 Fujifilm Corporation Lubricant composition, fluorine-based compound, and use thereof
US9117475B2 (en) 2009-03-25 2015-08-25 Fujifilm Corporation Lubricant composition and use thereof

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JPH07102271A (ja) * 1993-10-01 1995-04-18 Sony Corp 潤滑剤及び磁気記録媒体
ITMI20030992A1 (it) * 2003-05-20 2004-11-21 Solvay Solexis Spa Additivi perfluoropolieterei.
MY178172A (en) * 2015-07-31 2020-10-06 Fuji Electric Malaysia Sdn Bhd Ionic perfluoropolyether lubricant
CN108611156B (zh) * 2018-04-13 2022-03-18 天津长芦新材料研究院有限公司 一种氧化石墨烯型氟聚醚油脂添加剂及其制备方法

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US6761974B1 (en) 2001-05-04 2004-07-13 Seagate Technology Llc Polymeric lubricants with improved stability and thin film recording media comprising same
US20040044122A1 (en) * 2002-08-29 2004-03-04 Boldt Brent R. Ultraviolet radiation curable coating for MLS head gasket applications
US9117475B2 (en) 2009-03-25 2015-08-25 Fujifilm Corporation Lubricant composition and use thereof
US20100246064A1 (en) * 2009-03-27 2010-09-30 Hoya Corporation Lubricant compound for a magnetic disk, magnetic disk, and method of manufacturing the same
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US8492011B2 (en) * 2009-03-27 2013-07-23 WD Media (Singapore) Pte, Ltd. Lubricant compound for a magnetic disk, magnetic disk, and method of manufacturing the same
US20120231297A1 (en) * 2011-03-07 2012-09-13 Fujifilm Corporation Lubricant composition, fluorine-based compound, and use thereof
US8828565B2 (en) * 2011-03-07 2014-09-09 Fujifilm Corporation Lubricant composition, fluorine-based compound, and use thereof

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